Echo Base - a new PT2399 delay

[BoxOfSnoo]

Wow thanks, I love answers like that, I learn so much about how these circuits work!

I think a few of these might be easy enough to do, I think I'll take it one mod at a time, like you said.

I'm going to update the graphic, to help point out that capacitor.  I did notice that one too, just forgot to circle it.

[slacker]

Cool, I'll have a look at the original PCB and see if I can show how to add the mods. I presume the PCB John's using is the anonymousfacelesscoward one?
Looks like with a bit of trace cutting and a couple of extra jumpers the new buffers can be added to the PCB.

[BoxOfSnoo]

Cool, I'll have a look at the original PCB and see if I can show how to add the mods. I presume the PCB John's using is the anonymousfacelesscoward one?
Looks like with a bit of trace cutting and a couple of extra jumpers the new buffers can be added to the PCB.

Thanks again - I just got my PCB in the mail today (yay John!), and it does look like the anonymousfacelesscoward one, as you pictured here:
http://www.diystompboxes.com/smfforum/index.php?topic=60662.msg571675#msg571675

I'm getting rather excited to put this together.

[lucasventura]

The error is only on the schematic, the layout is OK. Whoever made it must have noticed the mistake and corrected it.

All the other layouts are correct as well.

Hello everybody! I have a doubt: the layout of Echo Base that link is totally correct? (Http://blogs.yahoo.co.jp/anonymousfacelesscoward/19192939.html).

I was reading this post and slacker said that the schematic was wrong. What is wrong?

Thank you all.

[mth5044]

Pretty sure that is right. Besides the 'Verified' on the top, I think the problem with the schematic was within the first few pages of this thread, but it got all fixed up. John Lyons made me an anonymousfacelesscoward PCB and it worked well.

[compuwade]

The error is only on the schematic, the layout is OK. Whoever made it must have noticed the mistake and corrected it.

All the other layouts are correct as well.

Hello everybody! I have a doubt: the layout of Echo Base that link is totally correct? (Http://blogs.yahoo.co.jp/anonymousfacelesscoward/19192939.html).

I was reading this post and slacker said that the schematic was wrong. What is wrong?

Thank you all.

I used this layout and it works great. The only issue with it is with the input buffer. It hisses a little with some amps. There is a thread with the fixes to this problem but I can't find it at the moment. Other than the little hiss, it sounds and works as described in the original post.

-Wade

[BoxOfSnoo]

Well, while troubleshooting my build, I let the magic blue smoke out of my only 78L05.    While I wait for another one... the bypass LED that goes to ground, is there an implied current-limiting resistor on that, or is it necessary?  I put one in while testing... I suppose it can't hurt, just wondering if I can simplify this a bit.

I did notice while it was working, that the LED was always on, no matter what position my switch was in.  No sound though...

While I'm asking dumb questions... I can't seem to find the pinouts for the 78L05 - on the datasheets I found it SEEMS to be output/gnd/input looking at it from the bottom - which means the parts layout I referred to above is backwards?  Is that layout supposed to be "component side" or "solder side"?  I wonder now about the other transistors and even if I blew up my ICs too.  Ugh.

[compuwade]

Well, while troubleshooting my build, I let the magic blue smoke out of my only 78L05.    While I wait for another one... the bypass LED that goes to ground, is there an implied current-limiting resistor on that, or is it necessary?  I put one in while testing... I suppose it can't hurt, just wondering if I can simplify this a bit.

I did notice while it was working, that the LED was always on, no matter what position my switch was in.  No sound though...

While I'm asking dumb questions... I can't seem to find the pinouts for the 78L05 - on the datasheets I found it SEEMS to be output/gnd/input looking at it from the bottom - which means the parts layout I referred to above is backwards?  Is that layout supposed to be "component side" or "solder side"?  I wonder now about the other transistors and even if I blew up my ICs too.  Ugh.

You do not need a resistor for the LED if you use the given connection from the PCB. However, from my experience the LED was very dim, so I used a limiting resistor and a DPDT footswitch to bypass the circuit and turn the LED off. This was better for me. If you use a superbright blue LED it should be plenty bright using the given PCB connection.

I believe the 7805 that was used in the original design was a TO-220 packaged version. It's a larger version that can handle more current than the 78L05. When looking at the flat side of the 78L05 (which is the version you have) the pinouts are: OUTPUT--GROUND--INPUT. When looking at the label side of the TO-220 version the pinouts are: INPUT--GROUND--OUTPUT. You can find this version at any radio shack if you are in the US.

[BoxOfSnoo]

Thanks, I think I've figured out the correct pinouts now.  What confused me was the TO-92 pin #1 is the OUTPUT...

They do have the same package in The Source here in Canada, but it's $5!  Is the higher current necessary (or worth it) for this project?  If not, I may get a handful from SmallBear even though it's $6 for shipping... 

[slacker]

Well, while troubleshooting my build, I let the magic blue smoke out of my only 78L05.

Impressive, I've always thought they were pretty indestructible.

   While I wait for another one... the bypass LED that goes to ground, is there an implied current-limiting resistor on that, or is it necessary?  

Like compuwade said you don't need a current limiting resistor there's already one on the board, it's the 10k connected to pin 8 of the CD4066. If the LED's not bright enough you could try making this smaller, I haven't tried this though.

Best thing to do for the 78l05 and the transistors is follow the datasheet for your particular ones rather than just following the layout. The other to watch out for is that on the layout the 2 TL072s are upside down so pin 1 is bottom right. If you've put them in the other way they are probably dead

[slacker]

They do have the same package in The Source here in Canada, but it's $5!  Is the higher current necessary (or worth it) for this project? 

No there's no need to use the 7805 the 78L05 is fine, I just used one because I had a load of them to hand.

[BoxOfSnoo]

Well, while troubleshooting my build, I let the magic blue smoke out of my only 78L05.

Impressive, I've always thought they were pretty indestructible.

I'm getting good at destroying parts!   I hope my 2 other chips survived the meltdown, those might be harder to find locally.

Like compuwade said you don't need a current limiting resistor there's already one on the board, it's the 10k connected to pin 8 of the CD4066. If the LED's not bright enough you could try making this smaller, I haven't tried this though.

Best thing to do for the 78l05 and the transistors is follow the datasheet for your particular ones rather than just following the layout. The other to watch out for is that on the layout the 2 TL072s are upside down so pin 1 is bottom right. If you've put them in the other way they are probably dead

Thanks, again good to know what those parts do.  I do have an ultra-bright LED on hand so that might fix it up if it bothers me that much.  I did notice the TL072 positioning as I was soldering the sockets on... I was like, "hey, why is this one solder pad kinda square and the others.... OHHHHHH...." (reach for desoldering pump).  At least I looked closely at that one.

I also discovered that the 2N5087 has a backwards pinout from the BC560, so I may need to replace that one too - at least for that one I wisely ordered spares.

[YouAre]

Slacker, I sent you a private message regarding some questions about the delay? Did you happen to get it?

[BoxOfSnoo]

After a whole lot of x-acto work (John, a lot of those traces are awfully close together) and finding one mistake in a resistor value... I got it to mostly work.  Right now I have the delayed signal louder than the direct signal, and the level pot does nothing.  Pin 15 of the PT2399 seems to give both signals equally strong, so the direct signal is not getting through for some reason.

The next issue after that is that when the tails switch is on, the bypass doesn't bypass... could these be related?

[slacker]

If the level pot doesn't do anything it's probably connected wrong, double check the wiring. I wouldn't worry about the bypass problem until you've sorted that out..

[BoxOfSnoo]

I did it!    It was more trace separation work that needed to be done.  Man I learned a lot about debugging this time around.  First time I used the audio probe successfully, actually...!

One question, there seems to be a fair bit of distortion in the repeats, is this inherent to the design of the circuit?

P.S. I really appreciate your help, you've been a great support and SUPER QUICK!  It's inspired me to do the same for others, if I can.

[slacker]

Glad you got it working. Some people have mentioned that it sounds a bit distorted especially with hot pickups, I've never noticed on mine.
The first thing to do would be to remove the 2 diodes connected to the feedback pot and see if that stops it.

This is what it's supposed to sound like if you want something to compare yours to, to me this demo sounds the most like my pedal.

http://www.youtube.com/watch?v=hNlSsMIK0s4

[Kev77]

hey slacker just finished mine.,.,. just nodding the head and grinning,, awesome

[BoxOfSnoo]

Glad you got it working. Some people have mentioned that it sounds a bit distorted especially with hot pickups, I've never noticed on mine.
The first thing to do would be to remove the 2 diodes connected to the feedback pot and see if that stops it.

This is what it's supposed to sound like if you want something to compare yours to, to me this demo sounds the most like my pedal.

http://www.youtube.com/watch?v=hNlSsMIK0s4

Yes, I see the diodes, that would make sense.  I may try lifting them and see what it sounds like.  I may even be able to put them on a switch if I can't decide which one I like better.

Ohh I watched that video many many times as I was contemplating building this pedal.  I think my delays are slightly dirtier than that... my pickups aren't all that hot, I do have a Seymour Duncan JB, which is hotter than typical but not insanely hot.  I'll play a bit with it (so easy to do now that it's working) and report back what the sounds are like.

[BoxOfSnoo]

Yes, I see the diodes, that would make sense.  I may try lifting them and see what it sounds like.  I may even be able to put them on a switch if I can't decide which one I like better.

Actually I have another thought, after reading how clipping diodes work.  According to a great post from R.G. a resistor in series with the diodes will blend in the straight signal.  Is this what the 20k resistor before the diodes accomplishes?  Would adjusting this value simply adjust the "dirtiness" of the delay?  Or, if I add a pot between the diodes and ground, will this let me dial in the amount of clipping?  Is there any practical limit (in either direction) for this resistor?

P.S. rewatching The Empire Strikes Back right now because of all of this